Metallurgy of zinc.



1'5. fumes, gasesor vapors.

, I furor-ED s'rarns PATENT OFFICE.

- CHARLES V. THIERRY, 015 PARIS, FRANCE.

METALLURGY OF ZINC.

1,030,349. It 0 Drawing.

'To all whom it may concern.

Be it known that I, CHARLES V. Tr-nnnnr, a citizen of the Republic of France, and a resident of the city of Paris, in said Republic of France, have invented certain urew anduseful Improvements in the l\letalinrgy of Zinc, of which the following is a sp'ecifi: cation. v I a This invention relates to the metallurgy of zinc and has for its object the utilization of certain materials, appropriately proportioned, acted upon by, electrically produced heat, whereby in a practical sense, all of the charged materials will be evolved and pass from the reaction chamber in the form of Many eiforts have been made to substitute the electrical furnace for the old extra- 'neously fuel-fired retort system. Several of these efiorts have been more or less success- 15111; but it is a fact, wellknown to those skilled in the art, that whatever may have been the ore and the rea ent employed it has 'usu'ally been necessary-to fluidify the residue (which generally requires the-addition of a 'fiux for the gangues) in order to withdraw it from the reaction chamber. Such residues and slags require special refractory material .to'resistvattack and erosion resulting in interruptions of the work and expensive renewals. I Moreover, steam, carbonic acid, sulifurous acid, etc., are generally. given ofi ,with harmful effects to one or more of the ,va'riousmaterials employed, or to phases of .the operation as for instance, the condensing portion of the process.

Pure oxid of zinc is asubstance usually in the form of powder containing 80.84; parts of zinc and 19.66 parts of oxygen by weight, chemically combined, but commercial oxid of zinc also 'contains certain impurities, the nature and proportion of which depend upon the method by which the oxid of zinc .1 .has been artificially produced.

The basis of this process is the treatment of ordinary commercial zinc oxid, namely an oXid which as above set forth is not chemically pure or even of a high degree of purity.

It is particularly observed that the symbolic formula of the classical reaction,

. only represents an abstract theoretical process; as a matter of fact, in practice, ore and coke or coal of variable constituent elements Specification of Letters Patent. t t d J 25, 1912 Applicationfiled October 6, 1911'. Serial No. 653,248.

are employedinstead of, strictly pure oirid ,coke or coal) one obtains in addition to the fumes and gases a residue which may be more or less solid, sticky, pasty or liquid gaseous impurities and unevolved portions of the metals in the ore.

My invention consists in charging, intermittently or continuously, a suitable electric furnacewith ordinary commercial or commercial oxid of zinc and with carbon in the form of coal or, coke, as for instance in. the actual proportions corresponding to the theoretical formula,

whereby the contents of the furnace chamber react equally one on the other and the two products of the reaction (Zn and CO) pass off automatically as and whenand at the rate produced, and in a gaseous form. As a consequence of this there is no residue and the operation may be carried on practically continuously and indefinitely. Incithe rapidity with which heat units can be furnished and the metallic reduction is essentially complete and changed to a form in which the products resulting therefrom are easily recoverable. In other words, the

electric furnace are thus realized for the recovery of the metals in the materials treated.

To obtain absolutely perfect resultswould require the employment of a chemically pure oxid of zinc and carbon. But such is not essential, nor practically nor commercially realizable. Moreover the degree of comin current practice yields entirely satisfactory results. Water, hydro-carbons, carbonic acid and other impurities capable of being vaporized can be removed by a preliminary heating, hence, the remaining impurities then contained in oxid of zinc and carbon,

tically consist of sulfur, silica, lime, ash andsimilar products less easily vaporized and. eliminated; but these elements are in of zinc and carbon. Theoretically the prodamountswhich are negligible, and they do.

and which may also be impregnated with dentally, the reaction may proceed with all ideal conditions for the utilization of the mercial purity which is readily obtainable as ordinarily obtainable generally and pracnot. sensibly, interfere with the new technical I effects already stated. At the most, itmay be necessary to manually remove from the react-ion chamber such 'sintered ash-slag as may have accumulated from .a run of long duration, that is, of weeks or even months. The removal of the sintered slag can therefore be made at a time when the process is not being carried out.

The-employment of, in the commercial sense, pure oxid of zinc and carbon, in

approximately the exact proportions necessary to produce a complete chemical reac tion when thermally acted upon. ell'ects several advantages of controlling imporuse ordinary fire-bricks for the furnace etc.

avoiding the necessary employment of tamped furnace chamber linings and various combinations of expensive refractories, such as magnesia, silica, chrome, carborundum,

Should oxid of lead, or oxid of cadmium,

be contained in the-oxid of zinc, it matters little since these oxids are also reduced'by the carbon. 1 In such instances, thecadmium passes offin the; form of a vapor; but the lead may be partially or wholly distilled or partiallyretai-ned as liquid metal on the furnace hearth, from whence it can readily be tapped. off. Q

VYhile it is not of oxid of'zinc and carbon shall be intimately mixed, this is nevertheless deemed preferable; as also. while not essential itis preferable that the carbon be crushed so as to pass through a'rather fine mesh screen.

'However it is quite feasible to feed the oxid and the carbon separately to'the furnace, say in layers, and "the oxid, especially may be considerably preheated before being reacted upon in the electric furnace, thereby.

minimizing thew-amount of electric energy required for producing the reaction.

It goes without saying that the zinc vapors may becornlensed or precipitated to the form ofnretali or in the formof blue powder or, gym 'to a veryrefined oxid. 'ofzinc, which gn any of the instancesmentioned presupposes the use of appropriate means, even 1 as; in the ordinary manner hitherto employed.

" The realization of this method while confined'to an electric furnace is noclimited to any particular type of-such furnace. This may be constructed according to the register,

essential that the charge to thejindnction, to the arc, or to "a tion of the resistor and of the arc principles. But, up to the present time, preference ;is

accorded to electric furnaces in which the resistance system of heat development is that the temperature of the furnace should be capable of complete control and the construction such as to exclude. air from the interior of the charge. y

I am aware that oxid of zinc has been employed in the classical fuel-fired'retort employed. Suffice to say, in this connection,

process, carbon being the reagent; but the purpose thereof has been for the partial enrichment of natural ores or concentrates. In the DGW'PIOCQiin which the electric furnace utilized, large charges may 'beacted upon and the heat units pass directly 'ithout intervening obstruction, into thematerial, whereas in the old process the of retorts and also through and to'the center ofthe contained. charge. Heretofore, the universal practice among zinc smelters. has been to add a considerable excess of carbon or displace the zinc in the ore. using the prior classical process there is the necessity for roastin sulfid ores; which, in practice, cannot be carried far enough to entirely eliminate the sulfur, entailing losses in the reduction and other difiiculties in conducting the operations. Hence under the old processes the reaction is long, irregular and incomplete; and alarge excess of pernicious, gases is 'evolved' which greatly in creases. the difliculty of condensation.

The condensation of zinc vapors into metallic zinc, upon a commercial scale, 1s;o ne I of the most delicate and perplexing problems known to metallurgy, and the rapidity and completeness with which this can be done largely constitutes the limiting factor as to the capacity of the electric furnace unit. This problem has been solved by my process, and by my process there is produced calories must be forced through the walls that is more than is necessary to liberate Then n a product containing zinc vapors which'can.

be delivered to a condenser (whatever, its

type or detail) with a minimum quantity of entrained gases.

The production, primarily, of oxid of zinc of ordinary commercial quality is simple and comparatively inexpensive, either by fuel-fired or electric furnaces, according to circumstances. in disclosed permits of the utilization'of blends of complex ores (oxids or sulfids) without. mechanical concentration, and, of slimes and ore-dumps which have hitherto been" regarded aspractically "valueless.

Therefore the method here-;

Moreover the use of thissystem does not require high-class labor.

, .Wmt I claim as. my invention is 1. In metallurgy, the method which consists in reducing, by electrically developed ng zone, a composite charge composed of commercial.metallic oxicls and carbon, the' said elements being electrically heated and the nature of the oxid being such that, when in heating the same, mixed with a commercially pure carbonaceous material, in an electric furnace from whose reducing zone air is excluded, the materials being in such pro- "portions as will effect, when heated to or above the temperature. of reaction, their complete conversion into fumes, gases, va-

pors, and an inert ashy or sintered residue,

the volatilized products being continuously evacuated as and when produced.

4. In.me tallurgy the method of reducing commercial zinc oxid which consists in heating the same, mixed with commercially pure coke or coal, in an electric furnace from whose reducing zone air is excluded, the materials being in such proportions as will effect, when heated to or above the temperature of reaction, their complete conversion into fumes, gases, vapors and an inert. ashy or sintered residue, the volatilized products being continuously evacuated as and when produced.

5. In the metallurgy of zinc the method which is comprised in progressively charging an electric furnace-with oxid of zinc of commercial purity and carbon and heating the mixture of'said oxid and carbon in the furnace to produce zinc fumes and withdrawing zinc fumesas and when produced, the carbon and oxid of zinc being in such proportion that substantially the entire charge will be changed into gaseous form.

6. In the metallurgy of zinc the method which is comprised in progressively charging an electric furnace with oxid of zinc of commercial purity and carbon and continuously heating the mixture of said oxid and carbon'in the furnace to continuously produce zinc fumes and withdrawing zinc fumes as and when produced, the carbon and oxid of zinc being in such proportion that-substantially the entire charge will be changed into gaseous form.

This specification signed and witnessed this 12th day of September A. D., 1911.

CHARLES V. THIERRY.

Signed in the presence of- Cn-mnms Lesson, H. C. 00x21. 

